fix readme check (Azure#18275)

Author: xiangyan99

eng/.docsettings.yml

@@ -145,6 +145,7 @@ known_content_issues:
   # HISTORY.rst
   - ['sdk/core/azure/HISTORY.rst','nspkg and common']
   - ['sdk/digitaltwins/azure-digitaltwins-nspkg/README.md', 'nspkg and common']
+  - ['sdk/nspkg/azure-messaging-nspkg/azure-messaging-nspkg/README.md', '#4554']
 
   # root readme
   - ['README.md', 'root readme']